Piston



May 28, 1935. B, DICK 2,003,011

I PISTON Filed Sept. 24, 1932 2 Sheets-Sheet 1 Fig.1.

Inventor BURNS DICK Att'y.

- May 28,1935. B. DICK- 2,003,071

PISTON Filed Sept. 24, 1952 2 Sheets-Sheet 2 Fig.5.

lnv en tor RNS DICK Att'y.

Patented May 28, 1935 STATES rArsr OFFICE Electric Corporation, ration of Delaware St. Louis, Mo., a corpo- Application September 24, 1932, Serial No. 634,703

11 Claims.

My invention relates to composite pistons which have their heads and skirts formed of material having difierent coefiicients of expansion. One of the objects of my invention is to provide improved means for securing the head and the skirt together which will permit the unequal expansion and contraction of the head and skirt, while at the same time preventing movement therebetween and maintaining the head and skirt concentric and firmly secured together under all operating conditions.

Another object of my invention is to produce a joint between the head and the skirt which will be strong and durable and which will permit the securing means therefor to be easily and economically assembled without weakening either the head or the skirt adjacent the joint.

Other objects of my invention will become apparent from the following description taken in connection with the accompanying drawings showing two embodiments thereof.

In the drawings Figure 1 is a side view, partly in cross section, of a composite piston showing my improved securing means; Figures 2 and 3 are cross sectional views on lines 22 and 3-3, respectively, of Figure 1; Figure 4 is a partial top View of the skirt; Figure 5 is a side view, partially in section, of a composite piston showing a modification; Figures 6 and '7 are cross sectional views on the lines 6-6 and 1-1, respectively, of Figure 5; and Figure 8 is a partial top view of the skirt shown in Figure 5.

Referring to Figures 1 to 4 of the drawings, l indicates the head of the piston which is preferably cast from either an aluminum or magnesium alloy and is provided with the usual ring receiving grooves 2 and the downwardly extending bearings 3 for receiving the wrist pin. The lower portion of the head forms a shoulder 4 and has a depending flange 5 carrying a plurality of radially extending peripherally spaced pro-- jections 6, the outer ends of these projections being offset inwardly from the periphery of the head.

The skirt 1, which is preferably made of drawn steel although it may be constructed of other material and by other methods, is provided at its upper end with peripherally spaced inwardly extending projections or flange portions 8. Each of these projections has a flat top portion for engagement with the shoulder 4 and downwardly extending inclined side portions forming a radially extending V-shaped groove in the lower side, as shown in Figure 2. A V-shapedslipper member 9 cooperates with the V-shaped groove of the projection 8 for a purpose which will presently be described. The projections B are adapted to fit into the spaces between the shoulder 4 and thev projections 6 of the head, the parts being assembled by positioning the projections 8 (with slippers 9 therein) between the projections 6 and then relatively rotating the head and skirt until the projections are in overlapping relation. The projections 8, in their assembled positions, are spaced slightly from the 10 flange 5 of the head, as shown.

Each of the projections 6 is provided with a vertical opening ID for freely receiving a coiled compression spring I I which is adapted to tightly compress the overlapping projections 8 against 15 the shoulder .4 by acting through the slipper 9 into which one end of the spring fits. The coiled compression spring is inserted from the bottom of the piston and the opening closed by means of a plug l2 which fits into a counter- 20 bored portion and is held in place by peening over the adjacent portion of the projection 6. The relation of these securing springs to the other parts of the piston is a very important feature of my invention. Since they are vertically positioned and are inserted from the bottom 'of the piston, it is not necessary to provide openings in the side of the skirt adjacent its top for their insertion, thus avoiding weakening the skirt. Accurate manufacturing tolerances are also not necessary in fitting the spring in the opening III. In order to additionally strengthen the top of the skirt, the portions between the projections 8 are provided with turned-over integral flanges l3.

In operation of the piston, the head thereof will have a greater rate of expansion. or contraction than the skirt, due to the difierence in material used. This difference in the rate of expansion and contraction in a radial direction, 40 is readily permitted by the slippers 9 which are adapted to freely move radially in the grooves of the projections I. The compression springs II maintain the projections 8 in contact with the shoulder 4 at all times notwithstanding the expansion and contraction of the head and skirt in a longitudinal direction. The springs are also of sufiicient strength to prevent separation of the shoulder from the skirt projections in movement of the piston in pressure applying direction. It is also to be noted that the head and skirt, when the piston is in operation, are at all times maintained concentric to each other as the springs and slippers prevent any relative horizontal movement.

' Referring to the modification shown in Figures 5 to 8, the skirt 1 is formed of drawn steel in the same manner as in Figure 1, the top, however, being provided with a continuous inwardly extending flange ll instead of the spaced apart projections. This flange is formed with radially extending serrations i5, as shown in Figures 6 and 8. The head 1, instead of being separately cast and then attached to the skirt, is cast directly onto the skirt as formed in the manner described. Due to the greater coeflicient of expansion 01' the material from which the head is cast, the head, upon solidification, will shrink away from the skirt at all points with which it is in contact during the casting, the space caused by this shrinkage being shown as exaggerated in the drawings; This shrinkage of the head will, therefore, make the skirt relatively loose on the head. In order to take up this looseness, and at the same time permit independent expansion and contraction of the head and skirt, I provide the depending circumferential flange I6 01' the head with a plurality of holes ill into which I insert the compression springs II for compressing the flange H of the skirt against the shoulder 4 of the head. These compression springs, as in the structure previously described, maintain the flange II in pressure engagement with the shoulder on the head notwithstanding expansion and contraction of the head and skirt, and are of suflicient strength to prevent longitudinal movement between the head and skirt during operation of the piston. Relative rotary movement between the head and the skirt is prevented by serrations I 5 on the flange of the skirt. The piston head, when in operation, will at no time reach the temperature at which it was cast, thus insuring that the skirt will not be deformed by the greater rate of expansion of the head.

Having fully described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. In a piston, a head member having a downwardly extending portion adjacent the periphery thereof and provided with a radial projection, a skirt member provided with an inwardly extending flange portion lying between the head member and the radial projection, a coiled spring carried by the radial projection and maintaining -the flange in contact with the head, the axis of the spring being parallel to the axis of the piston, and means comprising interengaging portions on the flange and the head member for preventing relative horizontal movement between the head and the skirt.

2. In a piston, a head member provided with a body portion and a projection, a skirt member provided with an inwardly extending grooved flange lying between the projection and the body of the head member, a member fitting in said groove, and resilient means carried by said projection and engaging said member for maintaining said flange in contact with the head, said member and resilient means being interengaged to prevent their relative movement.

3. In a piston, a head member provided with a plurality of projections, a skirt member provided with a plurality of radially extending grooved portions, each of said portions lying between a projection and the head member, a member fltting in each of said grooves, and a coiled spring carried by each of said projections and acting through said members for biasing each grooved portion of the skirt against the head member, the axis of said spring being parallel to the axis of the piston and the head of said spring being interengaged with said member to prevent relative movement therebetween.

4. In a piston, a head member provided with a portion having a recess opening radially outwardly a skirt member provided with a flange portion extending into said recess, said flange and a transverse wall of the recess which is perpendicular to the axis of the piston being provided with radially extending interengaging portions for preventing relative horizontal movement between the head and the skirt, and a coiled spring for compressing the flange against the head, the axis of said spring being parallel to the axis of the piston.

5. In a piston, a skirt provided with an inwardly extending flange, a head of different material than the skirt cast around the flange of the skirt, and means comprising an insertable expansible member cooperating with the head and skirt flange to prevent their relative movement in operation of the piston.

6. In a piston, a skirt provided with an inwardly extending circumferential flange, a head of different material than the skirt cast around the flange of the skirt, and means carried by the head for maintaining the flange of the skirt in pressure engagement with the head, said means comprising a plurality of compressible springs the axes of which are parallel to the axis of the piston.

7. In a piston, a skirt provided with an inwardly extending flange, a head of diflerent material than the skirt cast around the flange oi the skirt, and expansible means carried by the head for maintaining the flange of the skirt in pressure engagement with the head.

8. In a piston, a skirt provided with an inwardly extending circumferential flange, said flange being provided with a plurality of radially extending serrations, a head of difierent material than the skirt cast around the flange of the skirt, and means carried by the head ion maintaining the skirt in'p'ressure engagement with the head.

9. In a piston, a head member having a downwardly extending portion adjacent the periphery thereof and provided with a radial projection, said projection being provided with an opening which extends in the direction of the length of the piston, a skirt member provided with an inwardly extending flange lying between the head member and the radial projection, resilient means insertable in said projection opening from the interior of the piston for maintaining the flange in contact with the head member, and means for maintaining the resilient means in the opening and under compression.

10. In a piston, a head member having a projection provided with a passage extending in the direction of the length of the piston, a cylindrical skirt member provided with a flange portion lying between the head member and the projection, said skirt embracing the projection and being imperforate adjacent the flange and opposite the projection, and expansible means insertable in said projection passage from the interior of the skirt and cooperating with the projection and the flange for maintaining the flange in contact with the head member.

11. In a piston, a head member having a downwardly extending portion adjacent the pctionsand opposite the projections, and expansiriphery thereof and provided with a plurality of radial projections, each projection being provided with a passage which extends in the direction of the length of the piston, a cylindrical skirt member provided with flange portions lying between the radial projections and the head member, said skirt embracing the projections and being imperforate adjacent the flange porportions for maintaining the flange portions in 5 contact with the head. v

BURNS DICK. 

